1. Field of the Invention
The present invention relates to a speed change device for a tractor or another traveling vehicle.
2. Description of the Related Art
A traveling-type auxiliary speed change device disposed between an engine and a synchronous multi-speed speed change device exists in the associated prior art, as disclosed in the Japanese Laid-open Patent Publication No. 2007-145217. The device has a mechanism for switching between a high and a low speed and a mechanism for switching between forward and backward rotation, which are disposed in the stated order from the upstream side to the downstream side with respect to the direction of power transmission. The mechanism for switching between forward and backward rotation is configured so that a state in which traveling power is transmitted along a path from an engine to drive wheels becomes a state of disconnected power in association with a disconnecting operation of a clutch operation member that performs an engaging or disengaging operation.
In the mechanism for switching between forward and backward rotation, a driving force is converted into forward-rotation power via an idler gear supported on an idler shaft, and a composite multi-speed speed change device (a secondary speed change device or a super speed reduction device) is aligned in series rearward of the synchronous multi-speed speed change device.